<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        ul,
        li {
            margin: 0;
            padding: 0;
            list-style-type: none;
        }

        #lists {
            width: 700px;
            overflow: hidden;
            zoom: 1;
            border: 1px solid #333;
            margin: 0 auto;
            padding: 0 0 10px 10px;
        }

        #lists li {
            float: left;
            width: 128px;
            height: 128px;
            border: 1px solid #ccc;
            margin: 10px 10px 0 0;
        }

        #lists li img {
            float: left;
            opacity: 0.3;
            cursor: crosshair;
            /* filter: alpha(opacity=30); */
        }

        #lists li.now img {
            opacity: 1;
            /* filter: alpha(opacity=100); */
        }
    </style>
    <script>
        window.onload = function(){
            var lis = document.getElementsByTagName("li");
            for(var i = 0; i < lis.length; i++){
                lis[i].onmouseover = function(){
                    this.className = 'now';
                }
                lis[i].onmouseout = function(){
                    this.className = '';
                }
            }
        }
    </script>
</head>

<body>
    <ul id="lists">
        <li><img src="img/1.jpg" /></li>
        <li><img src="img/2.jpg" /></li>
        <li><img src="img/3.jpg" /></li>
        <li><img src="img/4.jpg" /></li>
        <li><img src="img/5.jpg" /></li>
        <li><img src="img/6.jpg" /></li>
        <li><img src="img/7.jpg" /></li>
        <li><img src="img/8.jpg" /></li>
        <li><img src="img/9.jpg" /></li>
        <li><img src="img/10.jpg" /></li>
    </ul>

</body>

</html>